1. Field of the Invention
The present invention pertains to the art of optical encoders, and more particularly, to the art of reflective optical encoders.
2. Art Background
Optical encoders are used in a variety of applications such as shaft encoders where an object's position or motion is sensed. In a reflective encoder, light from an emitter, usually a light emitting diode is directed at a coder such as a code wheel in the case of sensing rotary motion, or a code strip in the case of sensing linear motion. Specular reflections from reflective areas of the coder selectively reflect light from the emitter to a detector.
The performance of such an encoder and its resolution are limited by, among other considerations, the low degree of collimation of the emitter beam, diffused and scattered light caused by coder imperfections, and distortions due to encapsulation surrounding the detector.